1. Field of the Invention
This invention relates to a stepping motor utilizing the thickness slide effect of a piezoelectric material to generate rotary force of the motor and a method of driving such a stepping motor.
2. Prior Art
There has been known an ultrasonic motor comprising a piezoelectric device that utilizes the piezoelectric effect of deforming a dielectric body such as ceramic by applying voltage to it. FIG. 17 of the accompanying drawings illustrates such a known ultrasonic motor comprising a torsional vibrator 103, which is principally constituted by a piezoelectric device 101 and a coupler 102. As shown in FIG. 17, the main component of the coupler 102 is a disc-shaped member 107 having an indented edge portion 106 that comes into engagement with a matching protruding edge portion 105 of a resonator 104 placed contiguous to the piezoelectric device 101 and a projection 108 provided on the side opposite to the indented edge portion 106 in such a manner that they are positioned askance to each other so that the projection 108 is twisted as motive power when the disc-shaped member 107 is deflected by axial elongation or contraction of the resonant 104. When such a torsion vibrator is rigidly fitted to a rotor 109 as illustrated in FIG. 17, the rotor 109 will be allowed to rotate only in one direction.